The present invention relates in general to drives for deep well pumping installations. Pump drives of this kind include a stationary stand, rocking beam pivotable about a substantially horizontal first axis on the stand, a horse-head shaped rocking member which is pivotably supported on the rocking beam for a tilting movement about a second axis which extends transversely to the longitudinal axis of the rocking beam.
In pumping devices of this kind, used for example in recovering liquid from deep bore holes it is known to mount the horse-head piece on the rocking beam for tilting movement about an axis which extends transversely to the longitudinal axis of the rocking beam so that drilling or installation or maintenance operations in the range of the bore hole or of the pumping device can be performed. By tilting the rocking horse-head piece backwards, that means away from the bore hole, a lifting tool acting in vertical direction can be applied without problems. During the backward tilting movement of the horse-head piece, that means from a striking position into a position in which the aforementioned operations in the range of the bore hole, are performed, care must be taken that the horse-head piece, after passing the upper dead center of its path of movement does not drop on the rocking beam. This problem may occur also during the forward tilting movement of the horse-head piece. If during the forward tilting movement the horse-head piece strikes the rocking beam, hazardous, sparks may be created. For applying a pulling rope by means of which in cooperation with a lifting tool the aforementioned tilting movements are performed, in prior art horse-head pieces the operator must have stepped on the rocking beam in order to attach the pulling rope. This operation is not only unsafe but also very time consuming. In order to achieve an accurate vertical guide of the connection between the deep well pump and the polished rod engaging the horse-head piece, a certain adjustability of the position of the horse-head relative to the rocking beam must be provided. Conventional adjustment devices used for this purpose are complicated in construction and expensive in manufacture and moreover during practical operation they have the disadvantage that the operator cannot reach the individual setting elements from a single working position.